As businesses grow, the need to manage storage solutions for data produced and used by those businesses increases at a staggering pace. Storage is much more than just a collection of disk drives or tapes, it is a critical resource and must be allocated and managed as such in order to provide real benefits for a business. Consequently, methods and systems that allow for the efficient management and allocation of storage are needed.
Understanding data storage requires a review of both the hardware components involved with storage solutions and the virtual environment which makes use of those resources. At the lowest level of the data storage hierarchy are the actual storage mediums. These are the disks and other mediums on which software programs (e.g., applications) and the data used by those programs reside, in the case of disks, the digital information that makes up the programs and data is stored in magnetic form on a spinning platter and is accessed (e.g., read and written) using sensitive magnetic heads that traverse the platter.
Because disks are subject to mechanical failure, and to offer performance benefits, it is often the case that a number of individual disks are combined into a group. Multiple ones of such groups of disks may be integrated into larger storage infrastructures to make the data stored on the disks available to multiple computer systems over local or wide area networks. So-called Redundant Arrays of Independent Disks (RAID) are one means of grouping disks together. RAID systems can be fashioned in a number of different ways, each of which offer different, advantages and drawbacks.
Connecting, the disks to the other portions of a computer system are interfaces. These interfaces conic in a variety of forms, including various types of serial and parallel interfaces. Popular interfaces include the Small Computer System Interface (SCSI) and Fibre Channel (FC). Each interface has an associated communications protocol for managing the information exchange between the storage device and the attached computer system.
While very small computer networks (i.e., networks that do not support many individual users) may be able to make due with storage devices that are directly connected to (or integrated within) a few hosts (e.g., servers), such solutions are not appropriate for large computer networks in which many users require access to data, instead, larger computer networks often rely on independent networks of storage devices called storage area networks (SANs), A SAN, which may implement a block-based protocol for storage organization, is typically a high performance network in which the individual storage devices (and the storage servers that utilize such devices) are interconnected with one another by high speed interfaces (such as FC interfaces or Internet SCSI (iSCSI) interfaces) through one or more switches. Thus, a SAN acts like a fabric of storage devices.
Each of the storage servers and storage devices within the SAN connects with other such devices through a host bus adapter (HBA), a processing unit that handles intra-SAN communications. HBAs can be fashioned as expansion cards or integrated circuits within storage devices or servers, HBAs of different storage servers and/or storage devices exchange information via a switch that handles and directs traffic between these devices.
Of course, operating a SAN involves more than simply connecting servers and storage devises to one another. The storage devices must be configured, allocated, tested and maintained. Software systems designed for such activities are called storage resource management (SRM) applications, and these applications provide centralized management of an entire SAN through a single management console.
Another form of storage device technology is called Network Attached Storage (NAS). NAS systems use file access protocols, such as, for example, Network File System (NFS) or Common Internet File System (CIFS) to retrieve data and manage data at the file level. NAS solutions are typically less expensive than SANs and allow storage devices to be connected to computer networks through conventional Ethernet connections and Internet Protocol (IP) addresses, NAS devices can also be connected to a SAN. Like SANs, NAS devices are managed and configured using software applications that run on management consoles.